Chondroitin supplements can cause prostate cancer.
This rumor stems from preliminary research that suggests an association between chondroitin and prostate cancer.
One study found that chondroitin sulfate levels were higher in cancerous prostate tissue than in normal prostate tissue. And there's evidence that higher concentrations of chondroitin sulfate in the tissue around the prostate tumor may predict a more aggressive cancer.
Another in vitro study suggests that the chondroitin sulfate proteoglycan, versican, facilitates invasion of cancer cells into the prostate stroma.